263,513 research outputs found
Accretion disks in Algols: progenitors and evolution
There are only a few Algols with measured accretion disk parameters. These
measurements provide additional constraints for tracing the origin of
individual systems, narrowing down the initial parameter space. We investigate
the origin and evolution of 6 Algol systems with accretion disks to find the
initial parameters and evolutionary constraints for them. With a modified
binary evolution code, series of close binary evolution are calculated to
obtain the best match for observed individual systems. Initial parameters for 6
Algol systems with accretion disks were determined matching both the present
system parameters and the observed disk characteristics. When RLOF starts
during core hydrogen burning of the donor, the disk lifetime was found to be
short. The disk luminosity is comparable to the luminosity of the gainer during
a large fraction of the disk lifetime.Comment: 8 pages, 6 figures , accepted by A&
Canonical D = 1 supergravity framework for FLRW cosmology
We construct an extension of standard flat FLRW cosmology with matter,
possessing local D = 1, N = 1 proper-time supersymmetry. The fundamental
equation for the resulting mini-superspace models of quantum universes is a
Dirac-like analogue of the Friedmann and Wheeler-DeWitt equations. We provide
solutions of this equation for specific matter configurations based on the
supersymmetric O(3) and O(2, 1) sigma-models. It turns out that in the compact
model the volume rate of growth of the universe is quantized and non-vanishing
due to the zero-point energy of the scalar fields. In the non-compact model the
spectrum of the growth rates is continuous but subject to an uncertainty
relation involving the scale and the growth factor.Comment: 14 pages, no figure
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